A schwarz



Oct. 15, 1940- A. SCHWARZ PROCESS OF AND APPARATUS FOR REFRIGERATIONSheets-Sheet 1 Original Filed April 18, 1930 HTTZZENEYTS Oct. 15, 1940.

Original Filed April 18, 1930 A. SCHWARZ rnocass OF AND APPARATUS FORREFRIGERATION 2 Sheets-Sheet 2 Reirsued Oct. 15. 1940 UNITED STATESPATENT OFFICE PROCESS OF AND APPARATUS FOR REFRIGERATION August Schwarz,Chicago, IIL

20Claims.

The present invention relates generally to an improved process of andapparatus for refrigeration, and has reference more particularly to anovel process of refrigeration embodying the use of carbon dioxide (CO2)as the refrigerant. In certain respects, the' present invention is animprovement of that disclosed in my copending application Serial Number429,176, filed February 17, 1939.

One of the objects of the present invention re-.

sides in a novel process of refrigeration in which carbon dioxide as therefrigerant is condensed and cooled by means of cold brine havingapproximately zero Fahrenheit so that very low condenser pressure,resulting in an exceptionally low temperature of vaporization by lowsuction pressure, will be obtained.

Other objects reside in the provision of a new and improved process ofrefrigeration which comprises two stages for liquefying and vaporizingthe refrigerant to produce low temperatures by low condensing andsuction pressures, and in the preferred form of which the lowtemperature refrigerant is carbon dioxide. and the refrigerating mediumfor condensing the carbon dioxide is vaporized ammonia.

Further objects are to provide a novel refrigerating plant which may beutilized to accomplish the foregoing objects, and which comprises an arrangement of pipes and valves, for connecting the various operatingunits, adjustable at will to produce selectively any one of a pluralityof systems, for example, 1) a two stage system' adapted to operate atdifferent pressures, and (2) a single stage system in which theevaporator is adapted to be connected in a closed circuit with either awater cooled condenser or a brine cooled condenser, and (3) a splitstage system wherein the water cooled condenser may be connected withthe brine or gas cooled condenser and wherein the brine or gas cooledcondenser unit functions as an evaporator.

Another object of my invention is to provide a refrigeration systememploying carbon dioxide, or a similar refrigerant, having a brinecooled or a gas cooled condenser wherein the system operates with alesser amount of refrigerant, which would not condense under atmosphericcondition and wherein the refrigerant gas in the condenser is cooled bycold brine or gas and the carbon dioxide gas is only partly liquefledordensified. under low pressure, and whereby said partly liquefied ordensitled gasis expanded down to approximately atmospheric pressure orby creating a vacuum on the low side of the system.

Another object of the invention is in providing a low temperaturecondensing and cooling apparatus wherein the heat absorbing surface ofthe refrigerant evaporating passage is approximately twenty-five percent greater'than the heat transfer surface of the condenser passage.

Other objects and advantages will become apparent as the descriptionproceeds.

In the accompanying drawings- Figure l is a plan view of a plantembodying the principles of the invention.

Figure 2 is a horizontal sectional view of a combination evaporator andcondenser shown in plan in Figure 1.

Figure 3 is a sectional view along the line 3-3 of Figure 2.

Figure 4 is a horizontal sectional view through an evaporator, shown inplan in Figure 1, and

Figure 5 is a horizontal sectional view through a condenser shown inplan in Figure 1.

In the plant according to the present invention a condenser I2 isprovided through which a refrigerant is forced by pressure exerted by acompressor I4.

The refrigerant flows from said compressor through a pipe line 45 inwhich valves 51 and 50 are located and into a header 20 of condenser I2.The condenser I2 (see Figure 5) has a pair of header tanks 21 and 28 anda plurality of condenser tubes 29 connecting said two header tanks. 30

These tubes extend through the space 30 in the condenser I2. Theliquefied refrigerant flows from the header tank 21 through pipes 46 andBI and an expansion valve 02 into a combination evaporator and condenserII. This refrigerator unit I I (see Figures 2 and 3) consists ofevaporating tubes I1 connecting oppositely arranged header tanks 2| and22.

From the header tank 22', the refrigerant vapor is drawn oil by thecompressor 14 through pipes 11 and 44, and in said pipe line a pluralityof shutoff valves 56, 10,19 and 80 are provided. In this manner thecircuit of the refrigerant is closed.

The condenser I2 of this first refrigerating system is cooled by meansof fresh water which is forced by a pump 36 into the space 30 in thecondenser I2 through the pipe I08. From the space 30, the fresh water isdrained off through a pipe I09. Suitable valves 9 and I20 are interposedrespectively in the pipes I00 and I09. This condenser I 2 may be of anysuitable construction.

An exaporator I0 (see Figure 4) is provided, having two oppositelylocated header tanks 24 and 25 which are connected with each other bymeans of a plurality of refrigerating tubes 23, extending 55 arrangedand extend at right angles between the evaporator tubes II as shownclearly in the Figures 2 and 3, the condenser tubes connecting twoheader tanks I! and 20. Free passages are arranged in said unit forintroducing and withdrawing a fluid medium, said medium being in contactwith said condenser and evaporating tubes, if desired. coils or coilsand tubes may be arranged in said unit, and the construction of saidunit may be in the form of a shell or housins.

The refrigerant used in the second evaporator system is CO2. and thisrefrigerant leaves the condenser tubes l6 and the header tank 20 in theliquid condition through pipes 88 and 48, and flows through an expansionvalve 84 into the evaporator tubes 23. From here the refrigerant vaporis drawn of! through pipes 40, 65 and 86 by a compressor N, whichrecompresses and forces the refrigerant through a pipe line 61 into theheader tank I 9 and back into the CO: condenser tubes li.

The above shows clearly that in the plant according to the presentinvention, two refrigerating stages are present, and that the CO2 in thecondenser tubes I8 is cooled by means of the evaporator tubes l I, thatis, the refrigerant of the first refrigerating stage. It will be notedthat the unit II has a larger cooling surface than condensing surface,thus especially adapting the unit for low temperature operation, wherebyheat transfer is accomplished without excessive condensing surface.Within the broad concept of the invention, any suitable refrigerant orrefrigerants may be used in the two stages. If carbon dioxide is used asthe refrigerant in both stages, the pressure in the first stage will benormally high, but the pressure in the second stage will beexceptionally low. Carbon dioxide is .safe in use, and hence desirableas a refrigerant on shipboard. If ammonia is used as the refrigerant inthe two stages, the pressure in the second stage will be exceptionallylow. The use of ammonia in the first and carbon dioxide in the secondstage has the advantage that less power will be required with greateremciency in the present split stage system, using ammonia in the firststage and carbon dioxide in the second stage, than in a single stagehigh pressure carbon dioxide system, in which the condenser is cooled byfresh water.

It will be understood that the pressure in the second stage CO:condenser is subject to control by varying either the temperature or theamount of refrigerant therein. Thus, it is possible to operate thesecond stage condenser at a pressure higher or lower than from 300 to350 pounds at a given temperature, for example 0 l-"., by respectivelyincreasing or decreasing the amount of carbon dioxide employed.

Also, the operating pressure of the second stage condenser may bereduced below or increased above the aforementioned pressure range byrespectively decreasing or increasing the temperature in the condenser.Obviously, the operating pressure may also be changed by varying boththe temperature and the amount of carbon dioxide employed, that is tosay, that a pressure approximately from 100 to 500 pounds may bemaintained in the CO: condenser at a given temperature.

Before starting the second refrigerating system in which CO: is used asa refrigerant. the CO: in the condenser tubes II in the combination tankwill be cooled down to about zero Fahrenheit by the refrigerant in theevaporating tubes ll of the first refrigerating system. It

will be understood that both systems may be started at the same time ifdesired. If desired, a brine solution may be present in the spacesurrounding the evaporator tubes l1 and the condenser tubes I! in thetank II and may be circulated in said space by means of a brine pump 85and. a pipe line 84. Suitable valves ll and ll are arranged in the pipelines .84 at opposite sides of the unit ll.

If the pressure in the cm condenser originally is 900 pounds at atemperature 'of about "15 degrees above zero Fahrenheit, this pressurewill be reduced to about 300 to 350 pounds when the above mentionedtemperature of zero Fahrenheit is Obtfilllflly That means that thepressure will be reduced about 66 percent when the second refrigeratingsystem is started. and the liquid C0: will leave the condenser pipes Iiat approximately this temperature, and will enter the evaporator Ill atabout the same temperature.

In this evaporator, the liquid CO: is vaporized and is then drawn offand recompressed by the compressor l5. Since this CO: enters theevaporator at a very low temperature, and evaporates at a still lowertemperature, the suction pressure will be correspondingly low, so thatthe object of the invention is obtained, namely: Low temperature isproduced by low condenser and suc-' tion pressure.

On account of the heat created by compression of the CO: and the heatabsorbed by the housing or unit II, and the necessity of maintaining atemperature below the liquefaction temperature of the CO: and to permitheat transfer without excemive condenser surface in the CO2 condenser,the flrst refrigerating system has to have a capacity about 25 percenthigher than the second one, and in addition to the 25 percent highercapacity mentioned, provision must be made for any additional load whichmay be carried by the first system, and for that reason the first stagerefrigerating system must be provided with refrigerating tubes or coilshaving a greater heat absorbing capacity than the refrigerating tubes orcoils of the second system (if tubes or'coils are employed) and therefrigerating tubes If .in the CO: condenser are placed closer togetherand are more in number than the condenser tubes or coils l6.

By a pump 35, any suitable heat carrying medium may be forced throughPipes I03, I04, the CO1 evaporator space 28 and a pipe I" to a coolingroom (not shown). From the cooling room, this medium may be returnedthrough pipes llll and llll to the pump 35. The flow of the heatcarrying medium is controlled by valves I'll to H5 and I23.

Extremely low temperatures may be produced by reducing the pressure onthe low side of the CO2 system down to approximately atmosphericpressure or to a vacuum by employing the absorption method.

If desired, the tank ll may be eliminated and the fresh water cooledcondenser I! may be connected directly with the CO: evaporator by meansof the pipes 46, 41, 48, and expansion valve 64.

The refrigerant gas in the evaporator 13 will then be drawn oil andrecompressed by the compressor i4 through the pipes 40, 85, I4, 43 and44, and will be returned to the fresh water cooled condenser through thepipe 45. In this case the liquid refrigerant would enter the evaporatorill at a higher temperature than described before. and in consequence,the suction pressure would be correspondingly higher. Thus, the plantmay be converted at will into a single stage system.

The plant may also be operated as a single stage system with the unit IIas a condenser. In this event, brine may be utilized as the coolingmedium. The fresh water cooled condenser H with the compressor i 4 canbedisconnected by closing valves 55, 56, 80 and 83.

If the fresh water cooled condenser i2 is to be used in connection withthe refrigerating tubes II in the tank II, the valves 51 and 58 in thepipe line 45, valves 58 and 83 in the pipes 48 and II, the valves Oil,19 and I! in the pipe line 11 and the valve 86 in the pipe line 44 mustbe open. At the same time, valves ill and ii inthe pipe 41 and a valve55 in the pipe 43 must be closed. To connect the C: evaporator l0 withthe condenser tubes I8 in tank ii, valves 50, ii, 68, [0, II, 12, 13',62 and 83 in the pipes 40, 85, 68, 61, Cl and 48 must be open. When.however, the fresh water cooled condenser I2 is to be connected directlywith the CO: evaporator,

'the valves 83, I3, 80 and 18 must be closed while the valves 59, 80,Si, 82, 83, 50, 5|, 6!, I6, 15, 54, 55 and 56 have to be open.

It will be evident that I have provided a refrigerating system which maybe adjusted for use in different ways and which therefore is adapted tosatisfy widely varying demands. Thus, the entire plant, including bothstages, may be employed. In this event, brine may or may not be used inthe refrigerator and condenser unit II. If brine is used in the unit II,it will be available at the temperature prevailing in the unit for usein the cooling room (not shown). Assuming that brine is circulatedthrough the refrigerator ill, brine at two different temperatures willbe available from separate sources, namely, from the units Ill and II,respectively.

If the refrigeration requirements drop to such a point that the fullcapacity of the entire plant or system is not needed, the plant may beconverted into any one of a plurality of single stage systems of varyingcapacity. For example, one single stage system may include theevaporator ill, the compressor I5, the condenser tubes ii in the unit iiand the expansion valve 64, connected in series in the order named, andutilizing either brine or fresh water as the condensing medium in thespace I8 about the tubes It. It will be understood that when brine isused as the condensing medium, it ,will be obtained from an outsidesource at a suitably low temperature.

As an alternative expedient, another single stage system comprises therefrigerator Hi, the compressor I4, the fresh water cooled condenser l2and the expansion valve 64, connected in series in the order named. v

As a still further expedient, a third single stage system may includethe tubes H in the unit II as refrigerating tubes in contact with brineor any other fluid medium to be cooled, the comprmsor l4, the freshwater cooled condenser i2 and the expansion valve 82, connected inseries in the order named, preferably with ammonia as the refrigerant.

Thus, the refrigerating plant by reason of its convertibility at willinto any one of a plurality of single and double stage systems, has aflexible capacity adapted to satisfy widely varying refrigerationdemands. When the refrigeration demands are small, it would be wastefulto operate the entire plant at its maximum capacity, and

- hence one of the various single stage systems, best suited to theparticular demand, would be emp yed.

Having described my invention and how the same is to be used, I claim asnew, and desire to secure by Letters Patent:

1. In a two stage refrigerating system and method of producing lowtemperatures by low condenser and suction pressures two refrigeratingsystems adapted to cooperate with each other, the condenser of the firstsystem being cooled by fresh water. a combination evaporator andcondenser unit consisting of a closed housing containing therefrigerating tubes or coils of the first and the condenser tubes orcoils of the second system with brine passages therebetween, a by-pathconnecting the pipe line, leading from the fresh water cooled condenser,to the pipe conducting the liquid of low boiling point from thecondenser tubes of the second system to the evaporator of the samesystem, a second by-path connecting the suction line of the first systemwith the suction line of the second system, a valve adapted to preventthe entrance of the refrigerant into the evaporator tubes of the firstsystem, another valve arranged in the suction line of the first systembefore the junction of said line with the second by-path, a third valveinserted in the suction line of the second system right behind thejunction of the second by-path with said line, a fourth valve in thepipe conducting the liquid refrigerant of low boiling point to theevaporator of the second system and located between the outlet of thecondenser of the second system and the first by-path and a valve in eachof said by-paths.

2. A refrigerating system comprising, in com- I binati'on, a primarysystem having an evaporator, a compressor, a suction conduit connectingsaid evaporator to said compressor, a fresh water cooled condenserconnected to said compressor, an expansion valve'connected to dischargeinto said evaporator, a discharge conduit connecting said condenser tosaid expansion valve, a secondary system having a second evaporator, asecond compressor, a second suction conduit connecting said secondevaporator to said second compressor, a second condenser connected tosaid second compressor, said second condenser and said first mentionedevaporator being arranged in heat exchange relation for the transfer ofheat from the former to the latter, a second expansion valve discharginginto said second evaporator, a second discharge conduit connecting saidsecond condenser to said second expansion valve, a valve controlledconnection between the second condenser and said second dischargeconduit, a bypass conduit includinga control valve leading from saidsecond suction conduit at a point between said second evaporator andsaid second mentioned compressor to said first mentioned suctionconduit, and a by-pass conduit including a control valve leading fromsaid first mentioned discharge conduit to said second discharge conduit.

3. A refrigerating system comprising, in combination, a primary systemhaving an evaporator, a compressor, a suction conduit connecting saidevaporator to said conpressor, a fresh water cooled condenser connectedto said compressor,

an expansion valve connected to discharge into said evaporator, and adischarge conduit connecting said condenser to said expansion valve, asecondary system having a second evaporator, a second compressor, asecond suction conduit connecting said second evaporator to said secondcompressor, a second condenser connected to said second compressor, saidsecond condenser and said first mentioned evaporator being arranged inheat exchange relation for the transfer of heat from the former to thelatter, a second expansion valve discharging into said secondevaporator. and a second discharge conduit "connecting said secondcondenser to said second expansion valve. a by-pass conduit including acontrol valve for connecting said two suction conduits, and a bypassconduit including a control valve for connecting said two dischargeconduits.

4. A refrigerating systerncomprising, in combination, a primary systemhaving an evaporator, a compressor, a suction conduit connecting saidevaporator to said compressor, a fresh water cooled condenser connectedto said compressor, an expansion valve connected to discharge into saidevaporator, and a discharge conduit connecting said condenser to saidexpansion valve, a secondary system having a second evaporator, a secondcompressor, a second suction conduit connecting said second evaporatorto, said second compressor, a second condenser connected to said secondcompressor, said second condenser and said first mentioned evaporatorbeing arranged for the transfer of heat from the former to the latter, asecond expansion valve discharging into said second evaporator, and asecond discharge conduit connecting said semnd condenser to said secondexpansion valve, a by-pass conduit including a control valve forconnecting said two suction conduits, a control valve in said secondsuction conduit between said -by-pass conduit and said secondcompressor, a by-pass discharge conduit including a control valve forconnecting said discharge conduits, and a control valve in said seconddischarge conduit between said second condenser and said by-passdischarge conduit.

5. A refrigerating system comprising, in combination, an evaporator, anexpansion valve discharging to said evaporator, and two separaterefrigerant paths connected between the outlet of said evaporator andthe inlet of said valve, said paths being selectively available, onepath including a compressor and a brine and gas cooled condenser, theother path including a compressor and a water cooled condenser, and twoseparate paths arranged in said brine and gas cooled condenser, meansfor leading brine to and away from one of said separate paths, and meansfor leading a refrigerant to and away from the other of said separatepaths.

6. A refrigerating system comprising, in combination, a primary singlestage system including afirst evaporator, a compressor, a condenser, andan expansion valve connected in series in the order named, a secondsingle stage system including a second evaporator, a compressor, asecond condenser and an expansion valve connected in series in the ordernamed, said first evaporator and said second condenser being arranged ina single unit in heat exchange relation, means for circulating a fluidmedium through said unit to effect a heat exchange therebetween and tocool the fluid medium to a low temperature for outside use, and meansfor circulating a fluid medium through said second evaporator to cool'it to a low temperature, said systems being operable Jointly,

or one or the other may be operated single, by leading a fluid medium tobe cooled through said unit in connection with said first or primarysystem, or'by leading a fluid medium through said unit to cool thecondenser of the second system.

'7. A refrigerating system comprising, in combination, a compressor, acondenser, the inlet of said condenser being connected to the dischargeof said compressor, a refrigerating element connected to the dischargeof said condenser, an expansion valve interposed between said condenserand said element, the discharge of said element being connected to theinlet of said compressor, a second compressor, a second condenser havinga housing for enclosing said refrigerating element, said secondcondenser being connected to the discharge of said second compressor, arefrigerator or evaporator connected to the discharge ends of saidcondensers, a valve controlled by-pass be tween the outlet of the firstmentioned condenser and the outlet of the second mentioned condenserwhereby the refrigerant from said condensers may becommingled andexpanded into said refrigerator or evaporator, an expansion valve at theinlet of said refrigerator or evaporator, and valve controlled meansconnecting the discharge of said refrigerator or evaporator to saidcompressors.

8. A low temperature condenser and cooler comprising, in combination, ahousing defining a chamber, condenser and cooler means defining a closedpassage or passages extending through said chamber, means adapted tolead a medium to be condensed and cooled or a liquid to be cooledthrough said passage or passages, a refrigerating element or elementsdefining a closed passage or passages extending through said chamber andadapted to expand and evaporate a refrigerant therein to abstract heatfrom said first mentioned passage or passages, and means for leadingcold brine through said chamber, said brine and said vaporizedrefrigerant being employed singly or jointly to abstract heat from saidmedium passing through said condenser and cooler means.

9. A refrigerating system comprising, in combination, a first system anda second system, each including a compressor, a condenser, an expansionvalve and an evaporator connected in a closed circuit in the ordernamed, a heat exchange in which the evaporator of the first sys tem andsaid condenser of the second system are located and defining therewith acombination evaporator and condenser unit, means for leading a fluidmedium to be cooled through said unit, said first system having a muchgreater heat absorbing capacity than said second system so as to removethe heat of the second system and also to remove heat from the mediumpassing through said unit.

10. In a refrigerating apparatus, a combined evaporator and condensercomprising a single closed housing defining a chamber, two opposedheaders respectively at two opposite walls of said housing and havingmeans for introducing and withdrawing a refrigerant, a plurality of rowsof spaced condenser tubes connectingsaid headers and extending throughsaid chamber, two opposed headers respectively at two other oppositewalls of said housing and having means for expanding a refrigerant intoone of said last mentioned headers, and aplurality ofrows of spacedrefrigerating tubes connecting said last mentioned headers and extendingthrough said pressing,

chamber, and means for introducing and withdrawing brine from saidchamber.

11. A two stage refrigerating system consisting of two refrigeratingsystems, each system comprising a compressor, a condenser, an expansionvalve and an evaporator arranged in the order named to form two closedrefrigerating cycles, the first system employing-a refrigerant of highboiling point and the second plant employing a refrigerant of lowboiling point, the evaporator of one system and the condenser of theother system being arranged in a single closed shell or housing toconstitute a combined evaporator and condenser unit having a freepassage or passages for a fluid medium therethrough, valve controlledconnections whereby one of said systems may be disconnected from theother system and said combined evaporator and condenser unit then madeto function merely as an evaporator unit, and means whereby a fluidmedium to be cooled is circulated through the free passage or passagesin said unit.

12. In a two stage refrigerating system, a combined evaporator andcondenser unit consisting of a closed housing provided with two sets ofelements arranged in heat exchange relation and having freepassages'therebetween, the element of one set being a refrigeratingelement of one stage and the element of the other set being a condenserelement of the other stage, the refrigerating element of one stagehaving a greater heat absorbing capacity than the condenser element ofthe second stage and also having a greater heat absorbing capacity thanthe evaporating element of the second stage, and means 7 for circulatinga fluid medium through said passages in contact with both sets ofelements and for conveying the fluid medium to and away from saidhousing.

13. The process of producing low temperature without vacuum operationwhich consists in comcondensing, expanding and vaporizing a volatilerefrigerant in one path in a continuous cycle, circulating a refrigerantof low boiling point in a second path in a. continuous cycle, and withthe vaporizing portion of the first path in heat exchange relation withthe condensing portion of the second path, utilizing the low temperatureof the vaporized refrigerant in the first path to greatly reduce thepressure and temperature of the refrigerant on the high side of thesecond path, maintaining the low pressure and low temperature on thehigh side of the second path during operation, thereby greatly reducingthe power required in said second path, expanding and vaporizing the lowtemperature refrigerant of relatively low pressure by a correcycle,circulating a refrigerant of low boiling point in a second path in acontinuous cycle and with the vaporizing portion of the first path inheat exchange relation with the condensing portion of the second path,utilizing the low tempermedium in conta :t with the heat exchangePOrtions of the two paths, and utilizing the medium for outside use.

15. In a combination condensing and refrigerating apparatus, a closedhousing defining a chamber provided with a passage adapted to receive arefrigerant gas to be condensedand cooled to a low temperature, and arefrigerant cooling medium receiving passage for vaporizing arefrigerant therein, and a third passage adopted for introducing andwithdrawing a fluid medium to-be heated or cooled in direct contact withsaid other two passages, the last mentioned passage having a muchgreater heat absorbing surface than the condenser passage heat transfersurface, either two of said three mentioned passages may be operatedindependently.

16. A refrigerating system comprising, in combination, an evaporator, anexpansion valve discharging into said evaporator, and two separaterefrigerant paths connected between the outlet of said evaporator andthe inlet of said valve, said paths being selectively available eithersingly or jointly,'one path including a compressor and a water cooledcondenser, the other path including a compressor and a low temperaturebrine or gas cooled condenser.

17. In a two-stage split stage system, having a compressor and acondenser, a conduit connecting said compressor and said condenser, asecondary condenser, a liquid discharge conduit connecting saidcondenser and said gas cooled condenser, an expansion valve inserted insaid discharge conduit to supply refrigerant to-said gas cooledcondenser through said valve, an exhaust conduit opening from said gascooled condenser, and connected to the inlet of said compressor to drawoff the vaporized refrigerant and return the same to the first mentionedcondenser, an evaporator, a liquid discharge conduit opening from saidgas cooled condenser and connected to said evaporator, an expansionvalve inserted in said last mentioned discharge conduit to supplyrefrigerant to said evaporator through said valve, a conduit connectingthe discharge of said evaporator and the gas cooled condenser, acompressor inserted in said last mentioned conduit to draw on thevaporized refrigerant and return the same to the gas cooled condenser, avalve controlled branch conduit opening from said first mentioned liquiddischarge conduit, and a valve controlled branch exhaust conduit in saidfirst mentioned exhaust conduit.

18.. A refrigerating apparatus comprising, in combination, a housingdefining a chamber therein, a plurality of closed passages arranged insaid shell or housing and including said chamber, one of said closedpassages being adapted to expand and vaporize a'refrigerant therein,another of said passages being adapted for leading cold brinetherethrough, still another of said passages being adapted for leading agaseous medium to be condensed or a liquid to be cooled therethrough,said vaporized refrigerant and said cold brine may be employed singly orjointly to abstract heat fromsaidgaseousmediumorfromsaidliquid.

19. A split stage refrigerating system for producing low and moderaterefrigeration temperatures. consisting of two independent refrigeratingsystems cooperating with each other, said systerns permitting the use ofdiilerent refrigerants. the condenser element of one system and therefrigerating element of the other system being arranged in heatexchange relation ina heat exchange unit having a free fluid passagetherethrough, and means for leading a fluid medium to be heated orcooled in heat exchange relation with said elements to and away fromsaid unit, either one of said system when desired may be operated as anindependent refrigerating system to do useful refrigerating work.

20. In a refrigerating apparatus 'of' the character described, a closedhousing provided with a plurality of independent passages for condensinga refrigerant and for vaporizing a refrigerant and to receive a fluid tobe heated or cooled, each of said passages having separate inlets andoutlets whereby diilerent refrigerants and a medium to be heated orcooled may beeonveyed through said independent passages and in heatexchange relation with each other, the vaporizing passage being ofgreater capacity than the condenser passage.

AUGUST SCHWARZ.

